Apparatus and method for the storage of energy as heat
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Solution Overview
Problem
Pumped heat energy storage systems face challenges related to reliability, efficiency, and cost, particularly due to indirect contact heat exchangers which increase the size of heat exchangers and reduce efficiency, and the energy consumption of lockhoppers used to transport thermal storage media across pressure differentials.
Innovation Solution
A direct contact heat exchanger is used where the working fluid is brought into direct contact with solid thermal storage media, and a method involving transfer chambers and working chambers to transfer thermal storage media across pressure differentials, allowing for efficient energy storage and recovery by compressing or expanding working fluid while minimizing energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If indirect contact heat exchangers are used, then the heat exchanger size increases, but the efficiency decreases
Solution Approach 1:
The patent introduces thermal storage media as an intermediary substance that facilitates direct contact heat transfer between the working fluid and the heat storage system. The thermal storage media absorbs heat from the working fluid during compression and releases heat during expansion, eliminating the need for large indirect contact heat exchangers while maintaining high heat transfer efficiency.
Solution Approach 2:
The patent changes the heat transfer mode from indirect contact to direct contact between the working fluid and thermal storage media. This parameter change enables more efficient heat transfer with smaller equipment volume, as direct contact eliminates the thermal resistance of heat exchanger walls.
2Ease of operation
If lockhoppers are used to transport thermal storage media across pressure differentials, then the transport function is achieved, but energy consumption increases
Solution Approach 1:
The patent enables the thermal storage media to transport itself across pressure differentials by utilizing the pressure differential inherent in the thermodynamic cycle. The media is pressurized during the compression stroke and expands during the expansion stroke, eliminating the need for separate lockhopper mechanisms and their associated energy consumption.
Solution Approach 2:
The patent merges the thermal storage media transport function with the thermodynamic cycle itself. The same working fluid pressure changes that drive the heat storage and release processes also drive the transport of thermal storage media, combining multiple functions into a single integrated system.
3Productivity
If direct contact heat exchangers are used, then energy storage and retrieval rates increase, but the complexity of transporting thermal storage media across pressure gradients increases
Solution Approach 1:
The thermal storage media utilizes the inherent pressure differentials of the thermodynamic cycle to transport itself, eliminating the need for complex external transport mechanisms. The media is automatically pressurized and transported during compression and expanded during expansion, simplifying the overall system while maintaining high energy storage and retrieval rates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces energy losses and minimizes the size of heat exchangers, enhancing storage and recovery efficiency while allowing for high energy storage and retrieval rates, with the potential for significant cost reduction.
Implementation Method 1
a prime mover, driven by an energy source (for example an electricity supply) drives a compressor for working fluid within a working fluid circuit
Implementation Method 2
a first (high temperature/high pressure side) heat exchanger transfers energy from the working fluid to a heat store, being a mass of a material with a suitably high heat capacity, which heats up
Implementation Method 3
the pressurised working fluid which has given up heat is then expanded and cooled adiabatically by the action of the expander
Implementation Method 4
A second (low temperature/low pressure side) heat exchanger transfers energy from a cold store, being a further mass of material with a suitably high heat capacity, which is thereby cooled
Data Source
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AI summary
A pumped heat storage apparatus has a prime mover, a power take off, first and second fluid working machines functioning as a compressor (8) and as an expander (10), a working fluid circulation pathway with high and low pressure sides, and high and low temperature heat exchangers (18A-B). The heat exchangers operate using direct contact between gaseous working fluid and solid thermal storage media, such as glass beads, which move in opposite directions, typically using an augur (44). The system is reversible between energy storage and energy recovery modes and when it reverses, the direction of movement of the working fluid and the thermal storage media reverses. The apparatus may very rapidly swap between energy storage and energy recovery while having a high capacity and energy throughout.